Inherited deficiency of lysosomal acid maltase results in glycogen storage disease type II (GSD II) which results in disorders of varying severity. The investigator has characterized some of the molecular biology of the human acid maltase gene previously including cloning a cDNA for human acid maltase: isolating, sequencing and expressing the coding region; isolating and analyzing the structural gene; determining mutations for an acid maltase isoenzyme. This study will further characterize the molecular and biochemical properties of the mutant gene and protein from patients with GSD II with varying clinical phenotypes in order to correlate structure and function. The promotor and regulatory regions of the gene will be characterized. Dr. Martiniuk is the Co-Director of the Core Laboratory and the laboratory will be utilized for: DNA isolation, oligonucleotide synthesis, laminar flow hood use, blood separation, PCR, ultra- centrifugation, Western analysis, recombinant DNA techniques and ELISA.